1. Field of the Invention
The present invention relates to an apparatus for separating gaseous mixtures comprising a pair of separator vessels each packed with absorbent material such as silica gel, activated alumina or molecular sieves or absorbent material such as lithium chloride both serving as separating material, wherein a separating cycle during which air containing water vapor or gaseous mixture consisting of two or more different components such as nitrogen and oxygen is fed into one of said separator vessels to remove one or more components from the mixture and a regenerating cycle during which the processed gaseous mixture is partially fed into the other separator vessel to remove the quantity of components previously adsorbed or absorbed by the separating material present within this separator vessel and thereby to regenerate the separating material are alternately repeated.
2. Description of the Prior Art
As disclosed in U.S. Pat. No. 2,944,627, such apparatus for separating gaseous mixtures conventionally comprises a pair of main conduits each having an associated main separator vessel packed with adsorbent or absorbent material functioning as separating material are arranged in parallel with each other with inlet sides of the respective main conduits being connected to a common feed port while outlet sides of the respective main conduits being connected to a common discharge port. The main conduits are interconnected on their discharge sides by a bypass conduit including a stationary or variable throttle valve. A pressurized unprocessed gaseous mixture consisting of two or more different components such as air containing water vapor fed through the feed port is introduced alternately into the respective main conduits at predetermined time intervals by operating a plurality of switching valves provided in the respective main conduits so that the separating cycle during which the unprocessed gaseous mixture is fed into one of the main separator vessel to remove one or more components and this processed gaseous mixture is discharged through the discharge port and the regenerating cycle during which the processed gaseous mixture is partially introduced into the bypass conduit, then pressure-reduced through the throttle valve interposed in this bypass conduit and the processed gaseous mixture thus concentration-reduced is introduced into the other main separator vessel so as to remove the quantity of components previously adsorbed or absorbed by the separating material present in this separator vessel and thereby to regenerate the separating material may be alternately repeated to achieve continuous separation of one or more components from the unprocessed gaseous mixture. This apparatus operates on a principle that the adsorbent material such as silica gel or the absorbent material used as the separating material exhibits a unique characteristic of adsorbing or absorbing one or more components contained in the gaseous mixture or releasing them depending upon a relative concentration of the gaseous components to which the separating material is exposed. For example, in the case of dehumidifying gaseous mixture such as air containing water vapor by introducing such gaseous mixture into the separator vessel packed with adsorbent material such as silica gel and by separating said water vapor, the quantity of water vapor contained in the gaseous mixture per unit volume decreases in proportion to a pressure drop of the gaseous mixture as the latter is pressure-reduced and thereby expanded, so that a volume R of the regenerating gas required to release the moisture content previously adsorbed by the adsorbent material from unprocessed gaseous mixture at an absolute pressure P.sub.1 and of a volume Q is given by R=P.sub.2 /P.sub.1 .times.Q where P.sub.2 represents an absolute pressure of the regenerating gas. Therefore, P.sub.2 /P.sub.1 times the volume of the gaseous mixture dehumidified through the separator vessel into which the unprocessed gaseous mixture had been introduced and flowing out through an outlet may be fed into the other separator vessel to effectively dehumidify and thereby to regenerate the adsorbent material in this separator vessel. However, in practice, various factors such as a flow resistance encountered in the conduits, a pressure loss occurring in the separator vessels, a hysteresis of the dehumidifying characteristic of the adsorbent material, a temperature variation appearing in the separator vessels and a pattern of gas flow appearing within the separator vessels prevent the theoretical equation as set forth above from being established. With a consequence, the quatity of the dehumidified gas much more than the volume as defined by said pressure ratio is necessary for effective regeneration of the adsorbent material in the separator vessel on the regeneration side. Thus, an improvement in the efficiency of dehumidifying the unprocessed gaseous mixture has usually been limited to a certain level.